When the majority of Americans have been brainwashed into thinking that Global Warming is real and probably man-made, it becomes a losing topic to argue otherwise.
Imagine in the first debate a question for senator McCain that goes like this, “The latest Newsweek poll reveals that most Americans believe that Global Warming is a real problem and that the US isn’t doing enough to solve the problem. What is your solution?”
The good news is that McCain has effectively neutralized this issue. It probably won’t come up and if it does McCain will be ready with an answer that will appeal to the brainwashed independants.
Sometimes in baseball, a team will give up an out in order to score a run.
McCain is willing to ‘give up an out’ in order to get the conversation back to topics where he scores with the American people: National security, taxes/economy, backed by a lifetime of service/experiance.
That is a plausible stance.
Unfortunately, it is also a prescription for surrendering issue after issue, until nothing of importance remains.
Imagine that in 2004 the Swift Boat Veterans for Truth had adopted the approach you recommend. "We know that John Kerry's 1971 statements about US war crimes in Vietnam were vastly overstated and did great harm to veterans, but most people are persuaded that what he said was true. It's probably best just to leave the topic alone."
Instead, they opted to attack the Left's Big Lie about Vietnam directly, with evidence and with eyewitness testimony. And they won.